Vibrator



May 2, 196,1 K. E; A; JoELsoN 982,254

A T TORNEY May 2, 1961 K. E. A. JoELsoN' 2,982,254

VIBRATOR Filed sept. 2o, 1957' 2 sheets-sheet 2 Fly. 3.

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INVENTOR. /fA RL EVE/e7 A No5/Q5 -Jo EL 50N yA/yin /l TTORNEY.

States Patent v 1 vrRA'loRv l Karl Evert Anders Joelsom'Nykoping, Sweden, assigner to Aktiebolageft Industrikompaniet, Stockholm, Sweden, a` corporation of Sweden Fl'edSept. 20, 1957, Ser.` No. 685,299 `claims priority, application sweden May 24, 1951 "12.Clams.' (Cl. 121-16) The'present invention refers to a vibrator comprising a piston with projecting piston rod moving up and down in a cylinder and a valve body moving in avalve housing to Ydirect pressureuid tothe cylinder. The piston rod side' of the piston is subjected to permanentpressure from-a hydraulic pressure source andthe other side of the piston `is adapted to be alternately "connected with the pressure source andwith an'outlet according to the position of the valve. The invention aims at providing a vibrator of thistype that is simple indesign and with the hydraulic uid a's a power source can work at high frequency without disturbing noise.- An example of the use of the, Vibrator is rock 4drilling by. means of hard metal carbide tippedzpercussion drills or bores where it is desired tohave a percussion frequency higher than is possible with compressed air machines.

Thel main characteristic of the invention is that the valve body is adapted to be actuated by the motion of the piston by means of one or several spring members which cooperate with the piston during the whole of the stroke ofthe latter, as distinguished from the case with certain well-known' constructions where the springs cooperate withI the piston only when the latter reaches its end positions of the stroke. With the arrangement of the Vinvention, both the piston and the valve body operate as freely oscillating bodies without their end positions being positively vset byany ixed stops so that a fully developed oscillation will takev place. 'Ihe whole device therefore works quietly and with great speed. The said spring member can, for example, consist of two compression or coil springs acting against each other and preferably permanently engaging, under a certain pre-tension, a driver, dog or similar device between the piston and the valve'body. In this way the piston and the valve body movedas two .oscillating masses connected to each other through said spring system, when moving at the desired frequency (for example v*4,000 vibrations or strokesper minute or higherfor example 100046,00() vibrations or strokes per minute); TheY frequency andthe length of the stroke are ldependent ontthe spring constant, the qnantityof fluid andthe fluid pressure. An increased quantity of iluid impliesan increased piston -travel per unit of time and an increased fluid pressure implies an` increased. piston` acceleration. A weak spring implies long strokes, that is,l a low frequency, while av strong spring means shorter stro/kes, that is, a high frequency.

YThe invention will 'now be described ingreater detail with reference tothe morev or less diagrammatic longitudinal sections of someembodiments of the invention shown 'in Figures 1 and 2 on the accompanying drawings.

Fig. 2.a is an elevation of one of the valve elements of Fig. 2 per se.`

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Fig. 3 is'a longitudinal section of another embodiment of the invention,and

Fig. 4 is a top planvewthereof.

- `In Fig. `1`, 10 a cylinder in which a piston 11 is adapted tov move'faxially." The piston is mounted on a piston rod 12"or similar-device which passes sealingly through one end wall ofthe cylinder and which has an area preferably ice i Y 2 Y approximately half that of the piston 11. A valve spindle 13 is axially movable in a valve housing 14 which is iitted to vor is made integrally with the cylinder 10.`

tively, and apassage 20 leading to the cylinderv above the piston11. A pipe v21 from a hydraulic pressure source is in permanently open communication with the chamber under the piston 11 through a branch'pipe 22 and with the recess 13 through another passage 23. An outlet 24 leads from the recess 19.-

The movements of` thel piston 11 are transmitted Vto the spindle 13 via either of- .two springs-25, 26 which aretensioned against each other.

a clearance or vfree motion is fitted on the portion 28 of the valve spindle projecting outside the valve housing'. The springs engage the arm 27 and the abutments 29, 30, 0n the lvalve spindle; they are preferablyV pre-tensioned slightly. A movement ofthe piston 11 in either direction v rst compresses thecorresponding spring and then moves the valve spindle.`

vThe vibrator operates in the following way:

.'Ilhereis always a force acting on the bottom of the piston 11 which is equal to the specific pressure of the e hydraulic iluid multiplied by the annular piston area outside the piston rod 12, said area as mentioned above,

usually being about half the area of the top side of the -V piston. If the valve spindle 13 isin such-aposition that the valve head 16 affords an open Vcommunication betweenthe upper cylinder-v chamber Vand the outlet 24' while the hydraulic` fluid supplythrough the passage 23` is blocked by the valve head 15, then the piston will be subjected to an upward force equal fto half the piston area multiplied by the specichydraulic pressure. If on the other hand the valve spindle 13. is in the upper position so that the outlet 24 is blocked while the hydraulic uid is Vsupplied to the'uppery piston chamber through the recess 18, then the upper Side of thepiston will be subjected to a force which is equal to the Whole piston area multiplied by the specific hydraulic pressure. In this case, however, there -will act, at the same time, on the bottom of the piston an upward pressure which `is half as great, since said bottom is permanently actuated by the pressure from the pressure source. The resultant shown inthe figure, in which the supply of hydraulic liuid through the passage 23 andthe dischargekof uid through the passage '24 are -both blocked so that the specific hydraulic pressure in the upper part ofthecylinder is half that of the hydraulic pressurein the lowerI part. The moving elements of` the-.vibrator have a tendency, if they are not disturbed by loutside forces, to

move to this neutral position and even yafter being displaced from this neutral position to endeavour to resume it. They are however prevented `from remaining in this position because of the resilient coupling between;I

the' piston 11 and the valve spindle 13. If 'the piston has been -forced upwards under the action of an external force, as in the ligure, the spring l25 is compressedso that the valve. spindle 13 is A'pushed up. This opensr the .supply of hydraulic fluidthrough the passage 2?:Y andV blocks the outlet 24. The pressure on the top side of the In` thev diagrammatic 1 figure the pistonrod 12 has a driver arm 27 which with;-

piston 11 is greater and the piston is forced down. This compresses the spring 26 and in turn draws the valve spindle 13vdownwards. The hydraulic uid supply to the upper cylinder chamber is interrupted and instead communication with the outlet 24 is opened. The upwards forces on the piston 11 are prevailing so that the piston moves upwards. The whole process results ina rapid' reciprocating movement of theA piston 1L and consequently. also of the valve spindle 13'.- The neutralposition is alwaysy passed and the frequency of the movements ofthetwoelements is very high.

When a new stroke begins, the piston 11 will thus move at anl accelerating speed and will drive the valve spindle 13 inthe same direction but it should be notedl that due to the inertia of the-valve spindle and the spring coupling with-the piston, the valve spindle will lag behind and the spring will be compressedA by a force corresponding'to the acceleration force ofthe motion of the valve spindle. When -the valve spindle has passed the neutral position and arrives to the positionl in which the hydraulic pressure'is reversed the piston will be stopped and reversed but the valve spindle will continue further until the spring systemA has been released and stressed suiciently in the other direction to be able to slow down the valve spindle to stop it and then to start its movement in the other direcion.

The frequency and 'amplitude of the vibrator and its piston, respectively, can. be regulated by yaltering the strength or the length of the springs 25 and 26. A control canalso be provided Within limitsA by varying the hydraulic pressure and the quantity of fluid. The hydraulic pressure canl for instance be 50 to 100 kilograms/centimeterz. In one designwith 5,000 to 6,000 strokes a minute, the pressure was-70`kilograms/centimeter2; the liquid consumption, 120 liters/min.; stroke energy 6.4' kilogram meters/stroke; stroke length, 8 millimeters and piston speed, 6.5 metres/sec. The invention is, however, in no way limited' to these figures.

The hydraulic fluid may, for example, be oilk or water. In rock drilling ushing'water is fedV to' the drilling holes. The driving liquid required for the vibrator is about the same as the amount of lushing liquid needed. It is therefore possible when drilling at great depths, such as some 100 metres, to drive-the vibrator with water from the ground level without Aany supply of external energy since the energy due to-the level of water is suicient for driving the vibrator. The piston roti 12 can be connectedv directlywith the drill so that they both vibrate together, or the piston rod 12 and its associated elements can transmit their vibratoryV movement to the drill shank.

The invention can be applied in many other iields such as in excavating and loading'machnes; the vibrator then being coupled with the exacavating elements to facilitate their digging into` the material being loaded. Further applications-in which the vibrator can be used with advantage iare: releasing material in funnels and bins by shaking, conveying material in feed channels and dewatering of various materials (for example, thickening beaten pulp).

If the machine is used `as an impact machine the coupling between thepiston rod and the tool is adjusted so thatthe impact occurs before the piston motion meets the counter pressure for the liquid. 'I'his brakes the working piston so that the valve spindle catches up and reverses the direction'of motion;

If a pressure reduction valve or similar device is used soV that the hydraulicpressure on the piston rod side of the piston for instance is lower than the hydraulic pressure in the passage 23, the hydraulic forces acting on the two sides of the piston cannevertheless be made equal or approximately equal by a corresponding choice of the relationship between the outer diameters of the-piston and piston rod.

Fig. 2 shows an embodiment of the invention for use in a.. percussion drilling machine. This machine consists 4 of two concentric tubes 32' and 33. The liquidfissupplied between these two tubes while the inner tube 33 serves as outlet. The tubesY also guideV the machine-and rotate it in the drilling hole. The tube 32 is fixed to a casing 31, fitted with a block 34 which has a chamber 35 in which the slide valve heads 36, 38 canslide in axial direction so as to open and close communication between chamber 35 and an inlet passage 39, on one side and an outlet passage 40a, on the other side. Valve head 38 has a radiallyreduced portion 38a atI its end'facing the closed end portion of chamber- 35. This reduced portionl provides an annular groove through which the iluid in said closed end portion of chamber 35 may be dischargedvia outlet passage 40a. The valve heads 36, 38 are fixed on a valve spindle 37. The hydraulic uid enters froml the tube 32 to la passage 31a inside the casing 3 1 and passes from there through the inlet passage 39 but is prevented from entering chamber 35 while the valve head 36 is in the closed position as shown in the drawing. When the valve head 36 together with spindle 37 moves slightly outwardly from the Fig. 2 position in a direction towards the open end of chamber 35 the hydraulic iluid will be admitted to theportion of the chamber 3S located between the valve heads 36, 38; from here the uid can pass through the permanently open communicating passage 40 to a piston chamber 41 on one side ofthe piston 42. Inthis position valve headv 38 shuts off communication between the chamberA 35 and outlet passage 40a. When spindle 37 moves in the opposite direction so `as to carry valve' head 38 toward the closed end of chamber 35 communication is opened from chamber 35 to outletpassage-40a but communication between passages 39 and 35 is cut oflt. Outlet passage 40a communicates with a passage 40h leading-to the inner tube 33.

The valve spindle 37 extends coaxially through the piston 42 and mounted on this 'spindle are twoy collars or abutments 45 and 45a. The spindle37 is guided'axially by being mounted toslide through a third collar or abutment 43 xed in an extension 43a of the piston 42. Tensioned between said abutment 43 andthe abutments 45, 45a are counteracting springs 44, 44a. These springs correspond in function to the springs 25 and 26'in Fig. l. In addition the piston is lactuated by a spring- 46 which tends to force the piston 42, the spindle37 and thus the valve heads 36 and 381to the position in which valve head 36 opens communication betweenv inlet passage 39 and chamber 35 so as to start the machine by the action of the hydraulic fluid supplied to piston chamber 41 from inlet passage 39 via chamber 35 and passage 40 as soonl as said hydraulic uid enters the tube 32.

Onstarting the machine spring 46 forces the piston 42 downwardly in Fig. 2 and through the intermediary ofv springs 44, 44a piston *42 moves spindle 37 and. valve head 36 to the position in which said valve head. admits hydraulic fluid from inlet passage 39 into chamber 35 and from there through passage 40 to piston chamber 41 onv the lower side of the piston 42. The upper surface of the piston has a smaller effective area than its lower surface but also the upper surface is exposed to the pressure from the hydraulic uid which is supplied from passage 31a. Due to this difference in effective area the pressure on the lower side of the piston will predominate over the opposed pressure on the upper side of the piston plus the action of the spring 46so that the piston is caused to reverse its motion `and to move upwardly, carryingwith itself the spindle 37 and the valve system 36, 38, yet with a certain lag or delay on account of the elasticity of springs 44, 44a. When valve head 36 closesinlet passage 39 again during the upward motion the supply of hydraulic uid to the lower side of piston 42 ceases. After' a short period of time valve head 38 opens-communications between chamber 35 and outlet passage 40a so as to relieve the pressure on the lower side of piston 42.

Then said piston will reverse its motioniagain. Theioper ation is nowrepeated so that the piston 42.-together with,`

' direction or the other andduring continuous operation the spring system 44, 44u, serving as motion transmitting elements creates the suitation where the valve system may move in opposite direction to but synchronously with piston 42.

The piston stroke and frequency can be adjusted by a throttle screw 54 which can be caused to close the passage 40a to a higher or smaller degree. T'rhis adjustable throttle can also be tted elsewhere in the hydraulic sys-` tem.

The piston extension 43a contains a passage 47 which, through a constricted passage 48 and the space inside the casing 31, communicates with the inlet passage 31a for the hydraulic Huid. This restricted part of the hydraulic liuid ilowing to the passage 47 enters a passage 47a in the drill bar 50' and serves as ushing liquid while drilling. The Vibration movements of the piston 42 and its extension 43a are transmitted to the drill shank 49. The drill bar 50 can move axially but is prevented from rotating by suitable means engagedy therewith. A spring 52 pressing against a collar 51 on the drill bar 50 prevents the bar from falling out of the machine. A sealing ring can be tted in a peripheral .groove in the drill collar 51 to prevent ushing `liquid leaking away uselessly.

The machine shown in Fig. 2 ca-n be designed with dimensions small enough to allow it to be tted into the drilling hole itself so that `deep drilling can be done without having to t extension rods.

Figs. 3 and 4 show diagrammatically how the machine can be used to obtain a core of the material being drilled through. For this type of drilling it has hitherto been tively fixed reversing positions 4of their oscillation movements. v

2. A vibrator according to claim l, wherein two spring members acting in opposition and under compression engage said driver element.

3. A vibrator -according to claim 1, wherein the piston areas exposed to the pressure of said hydraulic fluid are dimensioned relative to the specic hydraulic pressure so that the pressure force acting on the piston rod side is at least approximately half of the pressure force on the other side of the piston.

4. Vibrator according to claim l, wherein the area of the piston exposed to the pressure of said hydraulic fluid on the piston rod side is half as large as that of the opposite side of said piston in the case that the specific hydraulic pressure is the same on both sides of said piston.

5. A vibrator according to claim l, whereinthe valve body and said spring means are arranged mainly concentric to the piston, and at least pantly within the latter. f

6. A vibrator according to claim l, wherein one of the inlet and the outlet passages of the hydraulic fluid to and from, respectively, the valve body-is adjustable for the control of the frequency and the stroke length of the vibrator. Y

7. A vibrator according to claim '1, wherein two tubes, coaxial with the piston, are arranged for the supply and discharge of lthe hydraulic liquid.

8. A vibrator according to claim l, wherein a spring is arranged in operative relationship with respect to the piston to urge the piston and the valve body towards a position in which the valve body opens a hydraulic fluid pass-age to one side of the piston on the supply of the hydraulic fluid to the vibrator.

9. Vibrator mechanism adapted for use in conjunction with a percussion drill including a rotatable tube, each .of said vibrators comprising in combination a cylinder customary to use la tubular drill bar which rotates around :the core and drills out the material so that the central core enters the space in the centre of the hollow dril-l.

Since the present invention makes it possible to producer small diameter machines, due to the high pressure of the hydraulic liquid it is now possible to use two or more of such drilling machines 55, 56 as shown in Fig. 3 connected to hydraulic supplyconduit and discharge conduit 59, 60 respectively and arranged on a common tube 58 which is rotated in the drilling hole 57 while the drilling machines effect their vibrating percussion movement and cut out the material byrmeans of the hard metal bits 55a, 56a. rI'he result is that the material is drilled out in a ring while leaving a centr-al core of material 58 inthe tube 54. k

The hydraulic percussion drilling or boring machine described can be used in this way to cut out drilling cores and gives a lower capital cost and higher drilling speed than can be obtained by earlier rotating drills.

What I claim is:

l. A vibrator comprising in combination a cylinder with a piston, having a piston rod, means for reciprocating said piston in said cylinder, a hydraulic pressure source, a valve housing with a valve body for supplying hydraulic uid from 'said pressure source to Vsaid cylinder so as to subject the piston rod side of the piston to a permanent pressure from said pressure source, means to connect alternatively the opposite sideof said piston with the pressure source and with an outlet for said tluid, respectively, according to the position of the valve body, and a driver element interposed between the piston and the valve body, and spring means operatively interconnecting the valve body with the piston through the intermediary of said driver element and'positively engaging with a piston, having a piston rod, means for reciprocating said piston in said cylinder, a hydraulic pressure source, a valve housing with a valve body for supplying hydraulic fluid from said pressure source to said cylinder so as to subject the piston rod side ofthe piston to a permanent pressure from said pressure source, means to connect alternatively the opposite side of said piston with the pressure source and with an outlet for said fluid, respectively, according to the position of the valve body, a driver element interposed between the piston and the valve body, and spring means operatively interconnecting the valve body with the piston through the intermediary of said driver element and positively engaging said driver element throughout the whole of the stroke of said piston, said piston and said valve body being arranged as freely oscillating bodies devoid of any positively fixed reversing positions of their oscillation movements, there being at said driver element throughout the whole of the stroke least two of said vibrators, means mounting said vibrators at the periphery of said rotatable tube of said percussion drill and rotatable therewith.

lO. A vibrator according to claim l wherein said piston and said valve bodies are arranged concentrically.

ll. A vibrator according to claim l wherein` said valve body and said spring means are arranged concentric to the piston.

12. A vibrator according to claim l wherein said valve body and said rspring means Iare arranged at least partly within said piston. l

References Cited in the tile of this patent UNITED STATES PATENTS 419,147 Falkenau Ian. 7, 1890 787,191 Krewson Apr. r11, 1905 1,665,046 Tucker Apr. 3, 1928 2,406,747 Davis Sept. 3, 1946 2,559,012 Davis et al. July 3, 1951 2,896,542 Forghieri July 28, 1959 FOREIGN PATENTS 947,975 Germany Aug. 23, 1956 

